The conference has been held to discuss the effects of tourism ________ the wildlife in the area
I wish to thank Mr. Lord, without _______ help I would never have got this chance.
________the cost, that will be very little.
The fact has worried many scientists ________the earth is becoming warmer and warmer these years.
The number of foreign students attending Chinese universities ________rising steadily since 2010.
Only then ________how much damage had been caused.